To recognize the 20th anniversary of the opening of the Pennington Biomedical Research Center in Baton Rouge, Louisiana, USA, a conference was held featuring some of the most prominent obesity researchers worldwide, addressing the most significant advances in obesity research. The Center had been founded with a gift from wealthy oilman Claude B Pennington with the mission of 'promoting healthier lives through research and education in nutrition and preventive medicine.' The purpose of the conference was to provide a cohesive presentation of the key events and steps that led to the major discoveries or advances in obesity science and give insight into new research directions. Only 20 of many possible topics could be adequately covered in the program of the conference. Their increasing importance is reflected in the increasing number of related publications as extracted from PubMed. The broad general areas in which these topics fall include measurement and evaluation of obesity, measurement of body composition and fat distribution, adipose tissue biology, genetics, bariatric surgery and public policy. Advances in the areas covered at the conference have had a major impact on our understanding of adipogenesis, central and peripheral regulation of body weight, health consequences of excess body weight, challenges of weight loss, magnitude of the worldwide epidemic and impact of public health policies.